Kolorimetrijska analiza i parametri stabilnosti UV-termokromnih boja

doctoral thesis

• Author: Rahela Kulčar
• Mentor: Marta Klanjšek Gunde (mentor)
• Committee member: Branka Lozo (član povjerenstva)
• Committee member: Nina Knešaurek (član povjerenstva)
• Committee member: Marta Klanjšek Gunde (član povjerenstva)
• Committee member: Maja Brozović (član povjerenstva)
• Committee member: Đurđica Parac-Osterman (član povjerenstva)
• Granter: University of Zagreb; Faculty of Graphic Arts; Zagreb
• Defense date and country: 2010-9-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Graphic Technology
• Universal decimal classification (UDC): 655 - Graphic industries. Printing. Publishing. Book trade

Abstract

Cilj predložene teme bio je istražiti efekte UV termokromnih tiskarskih boja te pomoću detaljne kolorimetrijske analize predložiti metodologiju korištenja i karakterizaciju ovih boja.

Analizirano je 12 termokromnih tiskarskih boja različitih aktivacijskih temperatura, proizvođača i fizikalnih karakteristika. Ispitivanjem fizikalnih karakteristika termokromnih boja, tretiranjem uzoraka kisikovom plazmom, dobio se uvid u stabilnost termokromne kapsule u odnosu na vezivo. Termokromne čestice pigmenata analizirane su pomoću pretražnog elektronskog mikroskopa (SEM).

Razvijena je metodologija koja daje jedinstveni instrumentalni način određivanja točnog modela mijenjanja boje i temperature na kojoj se ta promjena pojavljuje. Potvrđena je mogućnost kolorimetrijskog mjerenja termokromnih boja u kontroliranim uvjetima kako bi se osigurala velika ponovljivost mjerenja potrebna za kvantifikaciju dinamičkih karakteristika termokromnih boja. Kako bi se prikazalo kako termokromne tiskarske boje mijenjaju svoju boju, na različitim temperaturama, korišteni su prikazi krivulja spektralne refleksije kao i CIELAB sustav boja.

Za termokromne tiskarske boje određene su karakteristične temperature koje definiraju reverzibilni proces obezbojenja i obojenja. Spektralne refleksije TCX uzoraka mjerene su kroz tri različita ciklusa koji se razlikuju po temperaturnom području unutar kojeg su uzorci mjereni. Rezultati pokazuju da boja termokromnog uzorka ne ovisi samo o temperaturi, već i o termalnoj povijesti. Razvijen je model za izračun 3D površine petlje histereze kako bi se vidjelo kolika je uistinu reverzibilnost uzoraka. Detaljno je analizirana stabilnost termokromne boje unutar petlje histereze. Potvrđeno je da stupanj polimerizacije prilikom UV sušenja otisaka može utjecati na boju otiska u stanju obojenosti i obezbojenosti. Miješanjem termokromnih boja dobivene su nove boje različite dinamike promjene boja, ali i boljih karakteristika. Potvrđeno je da proces nije beskonačno reverzibilan, te da postoje faktori koji mogu uništiti taj proces i narušiti funkcionalnost termokromnih boja.

Abstract (english)

The aim of the proposed topic was to research the effects of UV thermochromic printing inks and to propose, by performing a detailed colorimetric analysis, a methodology of use and the characterization of these colours. Twelve thermochromic printing inks of various activation temperatures, producers and physical characteristics were analysed. By examining the physical characteristics of thermochromic inks and treating the samples by oxygen plasma, insight was gained into the thermochromic capsule's stability with respect to the binding material. Thermochromic pigment particles were analysed using a scanning electron microscope (SEM).

A methodology has been developed which provides a unique instrumental method for determining the exact model of colour change and the temperature at which this change occurs. The possibility of carrying out colorimetric measurements of thermochromic colours under controlled conditions whereby a high repeatability of measurements necessary for quantifying the dynamic characteristics of thermochromic colours would be ensured has been confirmed. In order to demonstrate how thermochromic printing inks change colour with temperature, spectral reflectance curves and CIELAB colour space were used.

The characteristic temperatures that define the reversible process of discoloration and coloration have been determined for thermochromic printing inks. Spectral reflexions of TCX samples were measured during three different cycles that vary depending on the temperature area within which the samples were measured. Results show that the colour of a thermochromic sample depends not only on temperature but also on its thermal history. A model for calculating the 3D space of the hysteresis loop was developed in order to see how reversible the samples really are. The stability of thermochromic ink within the hysteresis loop was analysed in detail. It has been confirmed that the degree of polymerisation during the UV drying of prints can influence the colour of a print in the coloration and discoloration state. By mixing thermochromic inks, new inks were obtained that besides exhibiting different dynamics of colour change, have better characteristics. It has been proven that the process is not indefinitely reversible and that there are factors that can destroy this process and undermine the functionality of thermochromic inks.

• Keywords: Termokromne tiskarske boje; mikrokapsule; temperatura aktivacije; reverzibilnost; UV polimerizacija; kolorimetrija; histereza; stabilnost boje
• Keywords (english): Thermochromic printing inks; microcapsules; reversibility; UV polimerization; colorimetry; hysteresis; colour stability
• Language: croatian
• URN:NBN: urn:nbn:hr:216:364321
• Study programme: Title: Graphic engineering and graphic product design; Course: Graphic technology; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti u području tehničkih znanosti (doktor/doktorica znanosti u području tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-04-24 22:21:34